Have you tried plugging in a second keyboard and taking over where necessary? I do a lot of remote work in which my colleague and I work on the same computer and it's quite useful for either of us to jump in with our own keyboard (and mouse). It does take a bit of occasional verbal negotiation to agree on who really knows what to do (and can do it fastest) but if you communicate well then it's pretty easy.
Can you say more about your setup? Does it require extra hardware/software?